Structural Changes Of Myoglobin Induced By Plasma Activated Water And Its Application On Color Developing Of Ham

As a new non-thermal physical processing technology,plasma is gradually applied to the surface sterilization and preservation of meat and meat products.Plasma activated water?PAW?,as a functional water,can be used as a source of nitrite to develop color for curing meat.Nowadays,few reports investigated on the color and structural changes of myoglobin induced by PAW,especially those which are based on different subtypes of myoglobin,and the interaction mechanism between active species and myoglobin is still unclear.This study took myoglobin as the research object,we used DBD and RF plasma device to produce DBD plasma activated water?DBD-PAW?and RF plasma activated water?RF-PAW?,respectively.Combining plasma physical chemistry and spectroscopy,this study tried to investigate the structural and color changes of the metmyoglobin?met Mb?and oxymyoglobin?oxy Mb?induced by the different PAW.Then the structural and color changes of met Mb and oxy Mb induced by H₂O₂solutions were further investigated.The mechanism of PAW oxidation effect on myoglobin structure and color was revealed and was applied in the color developing of cured ham,thus providing theoretical basis and scientific guidance for the engineering application of meat plasma preservation technology.The main results are as follows:?1?The study found that there was a significant difference between DBD-PAW and RF-PAW in the content and proportion of active species.DBD-PAW mainly accumulates H₂O₂,while RF-PAW mainly accumulates nitrite,resulting in stronger oxidation of DBD-PAW than RF-PAW.?2?The oxidability of both DBD-PAW and RF-PAW caused oxidization of oxy Mb into met Mb.But DBD-PAW has stronger oxidability,which leads to the destruction of the secondary structure of met Mb and oxy Mb.The tertiary structure of the outer globin was expanded and the tyrosine and tryptophan residues were gradually exposed.The structure of the central heme was destroyed.H₂O₂at high concentration was bind to myoglobin to form the Mb-H₂O₂complex.In terms of color,the reddish-brown met Mb solution turned green after discoloration.The oxy Mb solution changed from bright red to reddish-brown and then green.However,RF-PAW did not cause serious structural damage to met Mb,the heme structure was not degraded,and the Mb-H₂O₂complex was not generated.The color showed as follows:met Mb solution maintained reddish-brown,oxy Mb solution changed from bright red to reddish-brown,both showed no green substance generated.?3?H₂O₂solution at low concentration would interact with met Mb to form Mb-H₂O₂complex.Then it would lead to the heme degradation of met Mb,whose reddish-brown color was gradually faded and turned green.The H₂O₂solution oxidized oxy Mb into met Mb,then was bind with H₂O₂to form Mb-H₂O₂complex,with the heme's degradation in the end.Oxy Mb solution gradually changed from bright red to reddish brown and then significantly turned green.When the concentration level of H₂O₂in DBD-PAW was in the low concentration range,H₂O₂did not preferentially interacted with myoglobin.When the concentration of H₂O₂in DBD-PAW exceeded a certain range,it preferentially reacted with myoglobin,and the tertiary structure of outer globin was gradually expanded.H₂O₂combined with heme to form Mb-H₂O₂complex,and the heme was destroyed as well.?4?RF-PAW,nitrite solution and nitrite-H₂O₂mixture were used to produce cured ham respectively,all of which could produce pink color of fresh pork.H₂O₂in PAW and nitrite-H₂O₂mixture did not affect the color curing process of ham.PAW could create the best curing color since it produces more Mb NO pigment.There was no significant difference in nitrite residue between all the ham samples.If ascorbic acid was added to the pork system,the color developing was better and the nitrite residue of the ham samples was lower.